Mobile terminal and noise prevention structure of mobile terminal

ABSTRACT

A microphone ( 130 ) is fitted with a mounting portion ( 130   a ) of a front case ( 12 ) in a state being set to a microphone folder ( 134 ). A metallic mesh-wise sheet ( 132 ) is attached to a front face of the microphone. When an EL sheet ( 110 ) on a rear face of the front case emits light by supplying power to it, electrical noise is radiated from the EL sheet. The mesh-wise sheet of the front face of the microphone blocks the electrical noise from the EL sheet, which may enter through a sound hole ( 131 ) to the inside of the microphone.

REFERENCE TO RELATED APPLICATION

This application is a continuation application of Ser. No. 12/159,969filed on Jul. 02, 2008 which is the National Stage of PCT/JP2007/050762filed Jan. 19, 2007 which claims the benefit of the priority of Japanesepatent application No. 2006-012295 filed on Jan. 20, 2006, thedisclosure of which is incorporated herein in its entirety by referencethereto.

TECHNICAL FIELD

The present invention relates to a mobile terminal which is equippedwith a microphone and, more particularly, relates to a mobile terminalwhich reduces influence of electrical noise especially on a microphone.Furthermore, the present invention relates to a noise preventionstructure which reduces influence of electrical noise on a microphonewith which a mobile terminal is equipped.

BACKGROUND ART

In mobile terminals such as a mobile phone, a microphone of the mobileterminal may be affected by electrical noise generated by the mobileterminal itself. For example, a noise level of a voice signal outputfrom a microphone may increase because of noise generated by variouskinds of electrical components such as a transceiver circuit and aliquid crystal display unit, which are equipped in the mobile terminal.

In order to reduce the noise generated by various kinds of electricalcomponents in a mobile terminal, for example, Patent Document 1describes a noise prevention method which reduces high frequency noisegenerated by circuit boards which are equipped in a mobile informationterminal. In the noise prevention method described in Patent Document 1,the high frequency noise generated by the circuit boards which areequipped in the mobile information terminal is reduced by arranging aconductive substance between the circuit boards, or by forming aconductive substance with metallic foil or metallic plating applied to ahousing surface.

[Patent Document 1] Japanese Patent Application Laid-Open No.2003-264355 (Paragraph 0037 to 0042, FIGS. 2 and 3)

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

If the noise prevention method described in Patent Document 1 is used,the noise generated by the various kinds of electrical components in themobile terminal may be reduced to some extent. However, in the casewhere the various kinds of electrical components generate noise, it isnot possible to prevent the noise from entering the microphone.Therefore, there is a possibility that the noise level of the voicesignal outputted from the microphone increases because of the noisegenerated by the mobile terminal itself.

An object of the present invention is to provide a mobile terminal and anoise prevention structure of the mobile terminal, both of which canreduce the influence of noise on a microphone of the mobile terminal, inthe case where the mobile terminal itself generates noise.

Means for Solving Problems

According to the present invention, there is provided a mobile terminalequipped with a microphone, which includes: a housing component in whicha sound hole that is a hole for inputting a voice is formed; and ametallic sheet that is a sheet made by using metal 1 (for example,stainless steel), wherein the microphone is located at a portion wherethe sound hole of the housing component is formed, and arranged on theopposite side where a voice is inputted in the housing component, andthe metallic sheet is arranged between the housing component and themicrophone, and connected to a grounding portion of the mobile terminalby using a predetermined grounding method.

It may also be that the metallic sheet is attached to a face to which avoice is inputted in the microphone; and the microphone is mounted inthe housing component in a state where the metallic sheet is attached.

It may also be that the microphone includes a microphone body and amicrophone housing that is a housing for setting the microphone in; themicrophone housing is made by using metal; and the metallic sheet isconnected to the grounding portion of the mobile terminal via themicrophone housing.

It may also be that the metallic sheet is attached to a face on theopposite side to the face to which a voice is inputted, at the portionwhere the sound hole of the housing component is formed; and themicrophone is mounted in the housing component in a state where themetallic sheet is attached to the housing component.

It may also be that the housing component is formed a metal layerthereon that is a layer formed by using metal on the face on theopposite side to the face to which a voice is inputted; and the metallicsheet is connected to the grounding portion of the mobile terminal viathe metal layer.

It may also be that the mobile terminal further includes a connectionportion for connecting to an external device, wherein the connectionportion includes a conductor portion that is a metallic conductor whichis provided so as to surround a connecting terminal of the connectionportion, and is arranged on a face on the opposite side to the face towhich a voice of the microphone is inputted; and the conductor portionis connected to the grounding portion of the mobile terminal by using apredetermined grounding method.

It may also be that the mobile terminal includes a circuit board onwhich a predetermined circuit is formed such as a large scale integratedcircuit (LSI) for controlling a mobile phone and supplying a powersupply to an electroluminescent (EL) sheet, wherein the circuit board isformed a sound hole of the board side thereon that is a hole forinputting a voice, and arranged at a position on the opposite side towhich a voice is inputted in the housing component; the microphone,being located at the portion where the sound hole of the housingcomponent is formed, is mounted so as to be located on a face oppositeto a face fronting the housing component among faces of the circuitboard; and the metallic sheet is attached, on a face opposite to a facemounted the microphone among faces of the circuit board, so as to belocated at the portion where the sound hole of the housing component isformed.

It may also be that the circuit board is formed a grounding portionthereon; and the metallic sheet is connected to the grounding portion onthe circuit board.

It may also be that a mobile terminal is a mobile terminal equipped witha microphone, which includes a housing component in which a sound holethat is a hole for inputting a voice is formed. The microphone is formeda sound hole of the microphone side therein that is a hole for inputtinga voice, located at a portion where the sound hole of the housingcomponent is formed, and arranged on the opposite side where a voice isinputted in the housing component; and the housing component is made byusing metal, formed a sound hole therein apart from the sound hole ofthe microphone side by a predetermined length, and connected to agrounding portion of the mobile terminal by using a predeterminedgrounding method.

It may also be preferred that the metallic sheet is a sheet formed in amesh-wise shape.

It may also be that the microphone is arranged at the housing portionwhere an operation unit is arranged in the mobile terminal.

It may also be that the mobile terminal is a mobile phone.

According to the present invention, there is provided a noise preventionstructure of a mobile terminal which is equipped with a microphone,which includes: a housing component in which a sound hole that is a holefor inputting a voice is formed; and a metallic sheet that is a sheetmade by using metal. The microphone is located at a portion where thesound hole of the housing component is formed, and arranged on theopposite side where a voice is inputted in the housing component; andthe metallic sheet is arranged between the housing component and themicrophone, and connected to a grounding portion of the mobile terminalby using a predetermined grounding method.

Effect of the Invention

According to the present invention, the invention is configured suchthat a mobile terminal has a metallic sheet arranged between a housingcomponent and a microphone, and the metallic sheet is connected to agrounding portion of the mobile terminal. Therefore, in the case wherethe mobile terminal itself generates noise, the influence of the noiseon the microphone which is equipped in the mobile terminal can bereduced.

Further, in the present invention, a mobile terminal is configured suchthat a connection portion including a metallic conductor portion mountedon a grounding portion of the mobile terminal is arranged on a face onthe opposite side to a face to which a voice of a microphone isinputted. Consequently, a level of noise to be entered from a rear faceof the microphone in the inside of the mobile terminal can also bereduced.

Furthermore, in the present invention, a mobile terminal is configuredsuch that a housing component is made by using metal, a sound hole ofthe housing component is formed at a position being apart from a soundhole on the microphone side by a predetermined length, and a housingcomponent is connected to a grounding portion of the mobile terminal.Consequently, in the case where the mobile terminal generates noise, theinfluence of the noise on the microphone which is equipped in the mobileterminal can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view seen from a front face of a mobile terminalaccording to the present invention;

FIG. 2 is a block diagram showing a configuration example of a mobilephone;

FIG. 3 is a sectional view of a structure example of the mobile phone;

FIG. 4 is an explanation view showing a state where a portion includingan operation unit 124 of a housing portion of the mobile phone isexploded;

FIG. 5 is a sectional view showing one example of a specific mountingstructure of a microphone;

FIG. 6 is a sectional view showing a structure example of a microphoneelement;

FIG. 7 is a sectional view showing s structure including a microphoneand an input/output (IO) connector of the mobile phone;

FIG. 8 is a sectional view showing another example of a specificmounting structure of a microphone;

FIG. 9 is a perspective view in the case where a front case is seen fromthe rear face side;

FIG. 10 is a sectional view showing another example of a structure of amobile phone;

FIG. 11 is an explanation view showing a state where a housing portionincluding an operation unit of the mobile phone is exploded; and

FIG. 12 is a sectional view showing further another example of aspecific mounting structure of a microphone.

DESCRIPTION OF REFERENCE NUMERALS

-   12 Front case-   100 Mobile phone-   110 EL sheet-   120 IO connector-   124 Operation unit-   130 Microphone-   130 a Mounting portion-   131 Sound hole-   132 Mesh-   133 FET-   134 Microphone folder-   135 Tympanum-   136 Capsule-   137 Sound hole of Microphone-   140 Board-   150 Key sheet-   201 Connector terminal portion-   202 External conductor-   203 Outer coat portion

Best Mode For Carrying Out The Invention

Embodiment 1

A first embodiment of the present invention will be described withreference to drawings. First, a concept of a mobile terminal accordingto the present invention will be described. A mobile terminal like amobile phone includes a key sheet which uses an EL sheet in an operationunit, and the operation unit emits light by making the EL sheet emitlight. Furthermore, in the mobile terminal, a microphone (capacitormicrophone) is arranged in the vicinity of the EL sheet. When the ELsheet emits light, in the case where electrical noise generated by theEL sheet enters through a sound hole of the microphone to the inside ofthe microphone, a level of a gate of an field effect transistor (FET)connected to a tympanum of the microphone is fluctuated; andaccordingly, noise is generated in an output signal of the microphone.

In the present invention, a mesh-wise sheet made of stainless steel isattached to a front face of the microphone in order to avoid the abovementioned problems. This reduces a level of the electrical noise to beentered to the inside of the microphone. Furthermore, in order to reducethe electrical noise outputted from the rear face side of themicrophone, that is, from the side where a circuit board is arranged,the microphone is arranged on an input/output (IO) connector which isconnected to a ground (GND) and shielded. This reduces the noisegenerated in the output signal of the microphone.

FIG. 1 is a front view of the mobile terminal according to the presentinvention. As shown in FIG. 1, in the present embodiment, there will bedescribed a case where the mobile terminal is a collapsible mobile phone100. In addition, the mobile terminal may be a mobile phone other thanthe collapsible type. The mobile terminal is not limited to the mobilephone; but, the mobile terminal may be a terminal such as a personalhandy-phone system (PHS). In the present embodiment, a front face of themobile phone 100 is defined by a face including an operation unit 124and a display unit 125 of the mobile phone 100 in a state where thehousing is opened.

Further, as shown in FIG. 1, the mobile phone 100 is provided with asound hole 131 that is a hole for inputting a voice, on a housingcomponent which has a face including the operation unit 124. Amicrophone 130 is mounted on a rear face of the housing component wherethe sound hole 131 is provided. In the present embodiment, a surface ofthe mobile phone 100 is defined by a face which includes the operationunit 124 and the display unit 125 in the housing component, that is, aface which is visible from the outside. And, a rear face of the mobilephone 100 is defined by a face fronting the surface, that is, aninvisible face which is concealed in the inside of the mobile phone 100when the mobile phone 100 is seen from the outside.

FIG. 2 is a block diagram showing a configuration example of the mobilephone 100. As shown in FIG. 2, the mobile phone 100 includes an antenna11 for transmitting and receiving radio wave, a control unit 121, astoring unit 122, a radio communication unit 123, the operation unit124, the display unit 125, a camera unit (hereinafter, referred to as“camera”) 126, a ringer generator 127, a ringer drive unit 128, aspeaker 129 for voice output, and a microphone 130 for voice input.

The control unit 121 is composed of, for example, a central processingunit (CPU) and various kinds of peripheral circuits (not shown in thedrawing), and has a function for controlling respective units with whichthe mobile phone 100 is equipped.

The storing unit 122 is configured by, for example, a storage mediumsuch as a random access memory (RAM), and stores various kinds of datasuch as a control program in which the control unit 121 executes. Inaddition, one part of the storing unit 122 may be configured by a readonly memory (ROM), and a control program may be stored in the ROMportion.

The radio communication unit 123 has a function for modulating anddemodulating a signal in accordance with a predetermined communicationprotocol. More specifically, the radio communication unit 123 receives aradio signal via the antenna 11 and performs a demodulating process.Furthermore, the radio communication unit 123 modulates a signaloutputted from the control unit 121, and performs a transmitting processof a radio signal via the antenna 11.

The operation unit 124 is configured by key buttons which are forinputting phone numbers, for example. The operation unit 124 has afunction for outputting an input signal corresponding to a useroperation to the control unit 121.

The display unit 125 is configured by, for example, a liquid crystaldisplay (LCD), and arranged at a position that is the inside of thehousing when the mobile phone 100 is folded. For example, a standbyscreen, a function setting screen, and the like are displayed on thedisplay unit 125.

The camera 126, for example, has various kinds of functions with which adigital camera is provided, and includes an image sensor such as acharge coupled device (CCD) which captures an image of a photographicsubject, a circuit for outputting image data obtained by capturing animage to the control unit 121, and the like.

The ringer drive unit 128 has a function for outputting a drive signalto the ringer generator 127 in accordance with a control of the controlunit 121.

The ringer generator 127 has a function for generating a ring alert inaccordance with a drive signal of the ringer drive unit 128. Inaddition, a ring alert and a ringer melody are sounded from the speaker129, and a sound signal during telephone conversation is outputted froma receiver.

The EL sheet 110 is provided with a function of emitting light when apower supply is supplied from the control unit 121. In the presentembodiment, the EL sheet 110 emitting light causes a user of the mobilephone 100 finding that a key sheet of the mobile phone 100 appears toemit light.

Next, a configuration of the mobile phone 100 will be described. FIG. 3is a sectional view showing an example of a configuration of the mobilephone 100. In addition, FIG. 3 corresponds to a sectional view of a cutface (face A-A′ shown in FIG. 1) in the case where the mobile phone 100is cut at the center line in a longitudinal direction when the mobilephone 100 is seen from the front face.

As shown in FIG. 3, the mobile phone 100 includes an EL sheet 110, an IOconnector 120, a microphone 130, and a board 140. The EL sheet 110 isused for making the key sheet of the operation unit (124) emit light.The microphone 130 is used for inputting a voice signal during verbalcommunication. In the present embodiment, the microphone 130 is acapacitor microphone. The IO connector 120 is used for fixing themicrophone 130.

The board 140 is formed a predetermined circuit thereon. In the presentembodiment, the board 140 is mounted with an LSI for controlling themobile phone 100 and for supplying power to the EL sheet 110. As shownin FIG. 3, in the mobile phone 100, the EL sheet 110 and the microphone130 are mounted at the same housing portion of the mobile phone 100, andare mounted nearby.

In the mobile phone 100, the EL sheet 110 for making the key sheet emitlight and the capacitor microphone 130 are arranged nearby; andaccordingly, electrical noise caused by an AC drive voltage of 280Hz isgenerated between a positive plate and a negative plate of the EL sheet110 when the EL sheet 110 emits light. The electrical noise radiatedfrom the EL sheet 110 is entered to the inside of the microphone 130 viathe sound hole in which the microphone 130 has. As a result, a level ofa gate signal connected to the tympanum located in the inside of themicrophone 130 is fluctuated; and further, a level of the output signalof the microphone 130 is fluctuated. Then, noise is generated in thesignal of the microphone 130.

FIG. 4 is an explanation view showing a state where a portion includingthe operation unit 124 (FIG. 1) of the housing portion of the mobilephone 100 is exploded. As shown in FIG. 4, a key sheet 150 in which therespective key buttons of the mobile phone 100 are formed is arranged onthe rear face side of a housing component (hereinafter, also referred toas “front case”) 12 on the side including the operation unit (124).Furthermore, the EL sheet 110 is arranged on the rear face side of thekey sheet 150, that is, on the opposite side of the front case 12. Inthe present embodiment, a power supply is supplied from the control unit121 (FIG. 2) to the EL sheet 110 and the EL sheet 110 emits light; andaccordingly, it is possible to show to a user of the mobile phone 100 asif the key sheet 150 were emitting light.

The board 140 on which various kinds of control circuits are mounted isarranged on the rear face side of the EL sheet 110, that is, on theopposite side of the key sheet 150. The IO connector 120 for connectingthe mobile phone 100 to an external device such as a personal computerand a charger is connected to the board 140.

The microphone 130 is arranged on the surface side of the IO connector120. The microphone 130 is located on the rear face side of the portionwhere the sound hole 131 (FIG. 1) of the front case 12 is provided.

Next, a specific mounting structure of the microphone 130 will bedescribed. FIG. 5 is a sectional view showing one example of a specificmounting structure of the microphone (130). In addition, FIG. 5corresponds to a view shown by enlarging a portion which includes themicrophone 130 in the sectional view shown in FIG. 3.

As shown in FIG. 5, in the front case 12, a mounting portion 130 a formounting the microphone (130) is formed on the rear face side of theportion where the sound hole 131 is provided. Furthermore, themicrophone (130) includes a microphone element 130 c and a microphonefolder 134. The microphone element 130 c is fit in the mounting portion130 a of the front case 12 in a state being mounted to the microphonefolder 134. The microphone folder 134 is provided with a connectorportion (not shown in the drawing) which includes conductive rubber,springs, and lead wires. The microphone folder 134 can be made by usingan elastic material such as elastomer like synthetic rubber. Themicrophone element 130 c is electrically connected to a signal wire ofthe board 140 (FIG. 3) in the mobile phone 100 via the microphone folder134.

A mesh-wise sheet (hereinafter, referred to as merely “mesh”) 132 isattached to the front face of the microphone (130), that is, a face towhich a voice is inputted. In the present embodiment, the mesh 132 ismade of metal like stainless steel and formed in a twilled shape. In thepresent embodiment, the mesh 132 has a thickness of 0.12 mm, a wirediameter of 30 μm, an aperture of 33.5 μm (width of aperture portion),and an aperture ratio of 27.8%.

FIG. 6 is a sectional view showing a structure example of a microphoneelement 130 c. FIG. 6 corresponds to a structure of the capacitormicrophone element. As shown in FIG. 6, the microphone element 130 c isconfigured such that a microphone body which includes an FET 133 and atympanum 135 is set in a metallic capsule 136 like alloy includingcopper. A hole for inputting a voice (hereinafter, also referred to as“sound hole on the microphone side) 137 is provided on the front face ofthe capsule 136, that is, the face to which a voice is inputted.Furthermore, the mesh 132 is attached to the front face of the capsule136.

The mesh 132 is electrically connected to the capsule 136 by beingarranged so as to come in contact with the metallic capsule 136. Themesh 132 is electrically connected to a ground of the board 140 (FIG. 3)via the capsule 136.

As shown in FIGS. 5 and 6, the metallic mesh 132 is arranged on thefront face of the microphone (130). Consequently, even if electricalnoise is tried to be entered to the inside of microphone via themicrophone sound hole 137 (FIG. 6), the noise is blocked by the mesh132. In the present embodiment, the electrical noise radiated from theEL sheet 110 (FIG. 3) arranged adjacent to the microphone 130 ispossible to be entered via the microphone sound hole 137; however, itsinput is blocked by the mesh 132. This reduces a level of the electricalnoise to be entered to the inside of the microphone 130.

Furthermore, in the present embodiment, the microphone 130 is arrangedon the IO connector 120 which is shielded by being connected to theground (GND) (FIG. 4); and accordingly, the electrical noise outputtedfrom the rear face of the microphone 130, that is, from the oppositeside to the side to which a voice is inputted is also reduced. FIG. 7 isa sectional view showing a structure of a portion including themicrophone 130 and the IO connector 120 of the mobile phone 100. FIG. 7corresponds to a sectional view in the case where the portion includingthe microphone 130 and the IO connector 120 of the mobile phone 100 iscut at a face (face B-B′ shown in FIG. 1) perpendicular to alongitudinal direction of the mobile phone 100.

As shown in FIG. 7, the IO connector 120 includes a connector terminalportion 201 and a metallic external conductor 202 which is arranged soas to surround the connector terminal portion 201. The externalconductor 202 is covered with an outer coat portion 203 made by usingsynthetic resin or the like. Furthermore, the external conductor 202 isconnected to the ground of the board 140 (FIG. 3). As shown in FIG. 7,the IO connector 120 is arranged on the rear face side of the microphone130.

In the present embodiment, the IO connector 120 provided with thegrounded external conductor 202 is arranged on the rear face of themicrophone 130. This blocks the electrical noise outputted from the rearface side of the microphone 130, for example, the electrical noisegenerated by the EL sheet 110 (FIG. 3) and inputted from the inside ofthe housing.

The operation in which the mobile phone 100 makes the EL sheet 110 emitlight will be described with reference to FIGS. 1 to 6. In the mobilephone 100, if a predetermined light emission condition for making thekey sheet 150 (FIG. 4) emit light is approved, a power supply issupplied from a power supply portion of the board 140 to the EL sheet110. The light emission condition is, for example, incoming call, duringtelephone conversation, or user operation of the mobile phone 100. Whenthe conditions are approved, the power supply is supplied from a powersupply IC mounted on the board 140 to the EL sheet 110.

When the power supply is supplied to the EL sheet 110, the EL sheet 110emits light. When the EL sheet 110 emits light, a user can see a statewhere the key sheet 150 of the operation unit 124 emits light.

When the EL sheet 110 emits light, electrical noise is radiated from theEL sheet 110. At this time, the electrical noise radiated from the ELsheet 110 is possible to be inputted via the sound hole 137 to theinside of the microphone 130 which is arranged adjacent to the EL sheet110. In the case where the noise is inputted, a signal level of a gateof the FET 133 connected to the tympanum 135 (FIG. 6) of the microphone130 is fluctuated. As a result, noise is generated in a signal withwhich the microphone 130 deals, even in a state where a voice is notinputted to the microphone 130 or in a state where there is no ambientnoise around.

In the present embodiment, the electrical noise, which is generated bythe EL sheet 110 and is tried to be entered to the inside of themicrophone 130 via the sound hole 137, is blocked by the stainless steelmesh 132 attached to the front face of the microphone 130, that is, theface where the sound hole 137 (FIG. 6) is located. Consequently, theelectrical noise which is possible to be entered to the microphone 130can be reduced. Furthermore, the electrical noise which is tried to beentered to the inside of the microphone via the sound hole 137 of themicrophone 130 is blocked also by a shield effect obtained by connectingthe stainless steel mesh 132 to the GND of the mobile phone 100.Therefore, the noise which is possible to be generated in the signal ofthe microphone 130 can be reduced.

Still furthermore, in the present embodiment, the microphone 130 isarranged on the IO connector 120 which is connected to the ground (GND)and shielded. Therefore, the electrical noise which is tried to beentered through the rear face side of the microphone 130 to the insideof the microphone 130, for example, the electrical noise radiated fromthe EL sheet 110 can be reduced.

In addition, the microphone 130 is covered with the capsule 136 (FIG. 6)and connected to the GND of the board 140 via the microphone folder 134.Consequently, the influence of the electrical noise outputted from theside face side of the microphone 130 can be reduced.

The mobile phone 100 is provided with a mounting structure of the abovementioned microphone 130; and accordingly, the electrical noise whichmay be enter through the EL sheet 110 to the inside of the microphone130 can be blocked. This effect enables to reduce a noise generated inthe signal of the microphone 130.

According to the present embodiment, the stainless steel mesh 132 isattached to the front face of the microphone 130, and the mesh 132 iselectrically connected to the ground of the mobile phone 100. Thisstructure enables to reduce a level of the electrical noise to beentered to the inside of the microphone 130 via the sound hole 137 ofthe microphone 130.

Furthermore, according to the present embodiment, the microphone 130 isarranged on the IO connector 120 which is connected to the ground andshielded. This arrangement enables to block the electrical noiseradiated from the EL sheet 110, which enters through the rear face ofthe microphone 130 to the inside of the microphone 130. Consequently, inthe mobile phone 100 in which the EL sheet 110 is mounted in thevicinity of the microphone 130, it is possible to reduce generating ofnoise in a signal of the microphone 130 by the electrical noise due tolight emission of the EL sheet 110. Therefore, even if the mobile phone100 generates noise by itself, the microphone 130 of the mobile phone100 can reduce the influence of the noise.

In addition, in the present embodiment, there is described a method ofpreventing the electrical noise radiated from the EL sheet 110 frombeing entered to the microphone 130 adjacent to the EL sheet 110;however, intended noise for implementing the present invention may benoise generated by electrical components other than the EL sheet 110 inthe mobile phone 100. For example, a noise prevention structure (FIG. 6)using the mesh 132 can be applied to an application which reducesentering of noise generated by a liquid crystal display unit and atransceiver circuit in the mobile phone 100.

Embodiment 2

A second embodiment of the present invention will be described withreference to the drawings. In addition, in the present embodiment, asfor those similar to constitutional portions in the first embodiment,their detail description will be omitted; and those mainly differentfrom the first embodiment will be described.

FIG. 8 is a sectional view showing another example of a specificmounting structure of a microphone 130. In the present embodiment, amicrophone element 130 c is fit in a mounting portion 130 a of a frontcase 12 in a state being mounted to a microphone folder 134, as in thefirst embodiment (FIG. 5). Furthermore, the microphone element 130 c iselectrically connected to a signal wire of a board 140 in a mobile phone100 via the microphone folder 134, as in the first embodiment.

In the present embodiment, a water-shedding mesh 138 is attached to afront face of the microphone 130 in place of the before mentionedmetallic mesh 132 (FIG. 6). Furthermore, in the present embodiment, ametallic mesh 132 a is attached on the rear face side of a sound hole131 in the front case 12, that is, on a portion of the mounting portion130 a. In addition, the mesh 132 a is a sheet made of metal likestainless steel and formed in a twilled shape, as in the mesh 132 of thefirst embodiment. Furthermore, its shape has a thickness of 0.12 mm, awire diameter of 30 μm, an aperture of 33.5 μm (width of apertureportion), and an aperture ratio of 27.8%, for example.

FIG. 9 is a perspective view in the case where the front case 12 is seenfrom the rear face side. In the present embodiment, a metal layer 12 ais formed by applying metallic plating or the like to the whole of therear face side of the front case 12. The mesh 132 a (FIG. 8) iselectrically connected to a ground of the board 140 via the metal layer12 a.

In the present embodiment, the microphone element 130 c in which thewater-shedding mesh 138 is attached on the sound hole face side, thatis, on the side where a voice is inputted is electrically connected to asignal wire of the board 140 in the mobile phone 100 via the microphonefolder 134. The microphone element 130 c is fit to the mounting portion130 a of the housing case 12 in a state being mounted on the microphonefolder 134. In the front case 12, the stainless steel mesh 132 a isattached on the rear face of the portion where the sound hole 131 forthe microphone 130 is provided, and the mesh 132 a is connected to aground of the mobile phone 100. This can reduce a level in whichelectrical noise radiated from an EL sheet 110 arranged adjacent to themicrophone 130 is entered to the inside of the microphone 130.

Furthermore, in the present embodiment, the microphone 130 is connectedto the ground and arranged on a shielded IO connector 120. Therefore,the electrical noise outputted from the rear face side of the microphone130 can be reduced.

In the present embodiment, the microphone 130 is arranged as describedabove; and accordingly, the mobile phone 100 is provided with astructure which also reduces the electrical noise outputted from therear face of the microphone 130.

As described above, according to the present embodiment, the stainlesssteel mesh 132 is attached to the mounting portion 130 a of themicrophone 130 of the front case 12 and the mesh 132 is electricallyconnected to the ground of the mobile phone 100. This can block theelectrical noise to be entered to the inside of the microphone 130 viathe sound hole for the microphone 130. Therefore, in the case where themobile phone 100 generates noise by itself, it is possible to reduce theinfluence of the noise on the microphone 130 with which the mobile phone100 is equipped.

Embodiment 3

A third embodiment of the present invention will be described withreference to the drawings. In addition, in the present embodiment, asfor those similar to constitutional portions in the first embodiment,their detail description will be omitted; and those mainly differentfrom the first embodiment will be described.

FIG. 10 is a sectional view showing another example of a structure of amobile phone 100. In addition, FIG. 10 corresponds to a sectional viewin the case where a housing portion including an operation unit 124 ofthe mobile phone 100 is cut at the center line in a longitudinaldirection when the mobile phone 100 is seen from the front face. FIG. 11is an explanation view showing a state where the housing portionincluding the operation unit 124 of the mobile phone 100 is exploded.

As shown in FIGS. 10 and 11, a key sheet 150 is arranged on the rearface side of a front case 12, as in the first embodiment. An EL sheet110 is arranged on the rear face side of the key sheet 150. A board 140b is arranged on the rear face side of the EL sheet 110.

Furthermore, in the present embodiment, a microphone (capacitormicrophone) 130 b is mounted on the rear face side of the board 140 b.In this case, the microphone 130 b is mounted on the rear face of theboard 140 b at a position corresponding to a sound hole 131 in the frontcase 12, as shown in FIG. 10.

A metallic mesh 132 b is attached on the surface side of the board 140b. The mesh 132 b is attached so as to be located on the surface side ofa portion where the microphone 130 b is mounted in the board 140 b.Furthermore, the mesh 132 b is connected to a ground of the board 140 b.

A sound hole for passing a voice (hereinafter, also referred to as“sound hole of the board”) 141 is provided on the board 140 b.Therefore, a voice inputted via the sound hole 131 of the front case 12is inputted to the microphone 130 b passing through the sound hole ofthe board 141 via the mesh 132 b.

As shown in FIGS. 10 and 11, the metallic mesh 132 b is arranged on thefront face of the microphone 130 b, that is, on the side where a voiceis inputted via the board 140 b; and therefore, electrical noise isblocked by the mesh 132 b when the electrical noise is inputted via thesound hole 131 of the front case 12.

According to the present embodiment, the stainless steel mesh 132 isarranged on the front face of the microphone 130 via the board 140, andthe mesh 132 is connected to the ground of the board 140. This canreduce a level of the electrical noise to be entered to the inside ofthe microphone 130. Therefore, in the case where the mobile phone 100generates noise by itself, it is possible to reduce the influence of thenoise on the microphone 130 with which the mobile phone 100 is equipped.

Embodiment 4

A fourth embodiment of the present invention will be described withreference to the drawing. In addition, in the present embodiment, as forthose similar to constitutional portions in the first embodiment, theirdetail description will be omitted; and those mainly different from thefirst embodiment will be described.

FIG. 12 is a sectional view showing further another example of aspecific mounting structure of a microphone 130. In the presentembodiment, a microphone element 130 c is fit to a mounting portion 130a of a front case 12 c in a state being mounted on a microphone folder134, as in the first embodiment (FIG. 5). Furthermore, the microphoneelement 130 c is electrically connected to a signal wire of a board 140in a mobile phone 100 via the microphone folder 134, as in the firstembodiment.

In the present embodiment, a water-shedding mesh 138 is attached to afront face of the microphone 130 in place of the metallic mesh 132. Inthe present embodiment, the front case 12 c is metallic and die-cast.Furthermore, the front case 12 c is grounded to a ground of the board140.

A sound hole 131 c for inputting a voice is provided in the metallicfront case 12 c. The sound hole 131 c is provided in the front case 12 cso as to differ in the location of the sound hole 137 c of themicrophone 130 which is fit in the mounting portion 130 a.

The front case 12 c is made by using metal; and therefore, electricalnoise which is tried to be entered through the sound hole 131 c of thefront case 12 c to the inside is blocked by the metallic front case 12c.

According to the present embodiment, the front case 12 c is made byusing metal, and the sound hole 131 c is formed in the front case 12 cso as to differ in the location of the sound hole 137 c of themicrophone 130. Therefore, the electrical noise to be entered to theinside of the microphone 130 passing through the sound hole 137 c of themicrophone 130 can be blocked. Therefore, in the case where the mobilephone 100 generates noise by itself, it is possible to reduce theinfluence of the noise on the microphone 130 which is equipped in themobile phone 100.

The present invention can be applied to mobile terminals such as amobile phone and, more particularly, can be applied to an applicationwhich reduces influence of noise in a mobile terminal which is equippedwith a microphone.

What is claimed is:
 1. A mobile terminal equipped with a microphone,comprising: a housing component in which a sound hole for inputting avoice is formed; a metallic sheet, the microphone is located at aportion where the sound hole of the housing component is formed, andarranged on an opposite side of a surface of the housing component incorrespondence to the sound hole, the metallic sheet is arranged betweenthe housing component and the microphone, and connected to a groundingportion of the mobile terminal by using a predetermined groundingmethod, an electroluminescent (EL) sheet is arranged in an operationunit, the metallic sheet is attached to a face of the microphone towhich a voice is inputted in the microphone, the microphone with theattached metallic sheet is mounted in the housing component, themicrophone includes a microphone body and a microphone housing in whichthe microphone body is disposed, the microphone housing is made ofmetal, the metallic sheet is connected to the grounding portion of themobile terminal via the microphone housing, the mobile terminal furthercomprises a connection portion for connecting the mobile terminal to anexternal device through a connecting terminal of the connection portion,the connection portion includes a metallic conductor portion thatsurrounds the connecting terminal to shield the connection portion, theconnection portion is arranged on a rear face of the microphone which isan opposite side to a face to which a voice is inputted in themicrophone, a part of an outer face of the metallic conductor portionbeing opposed to the rear face of the microphone to shield the rear faceof the microphone, and the metallic conductor portion is connected tothe grounding portion of the mobile terminal by using a predeterminedgrounding method.
 2. The mobile terminal according to claim 1, whereinthe metallic sheet is a sheet formed in a mesh-wise shape.
 3. The mobileterminal according to claim 1, wherein the microphone is arranged at thehousing portion where an operation unit is arranged in the mobileterminal.
 4. The mobile terminal according to claim 1, wherein themobile terminal is a mobile phone.